1. Field of the Invention
The present invention relates to a method for detecting users' pressing action, particularly to a method for detecting users' pressing action by optical method and an optical operating unit using the method.
2. Description of Related Art
With the progress of the plane display technique, more and more electronic products assembled with a screen. Many electronic products are operated by moving a cursor on screen. There are many operation interfaces to control the cursor. Touch pads are one kind of these operation interfaces which integrate with a function of moving the cursor and a function of the key. The capacitive touch pad and the resistive touch pad are popular touch pads. The resistive touch pad lacks good sensitive, so that the resistive touch pad may be damaged with strong force exerting thereon by a user. However, the capacitive touch pads have high cost, and are easily to make misoperation caused by electrostatic force or humidity.
The touch pads are not suitable for being applied to portable electronic apparatuses with small size (such as mobile phones). An U.S. Pat. No. 7,058,432 discloses a pointing device applies to a portable electronic apparatus with small size. This pointing device can detect a movement of a finger by an optical method to cause a corresponding movement of a cursor on the screen.
However, the above pointing device can move the cursor on the screen, but can not provides a pressing function. Another pressing key is needed for the user to perform the pressing action. Therefore, the above pointing device take a large space so that the size of the electronic apparatus can not be further reduced. Further, the production cost of the electronic apparatus is increased.